9A: Classification

Question 1

What is taxonomy?

Answer 1

The study of classifying organisms

Originally established by Carl Linnaeus based on morphological and behavioral data.

Question 2

What modern evidence is used in classification?

Answer 2

• Genome sequences
• Protein sequences

These are used to determine relatedness among organisms.

Question 3

List the eight levels of the taxonomic hierarchy from broadest to most specific.

Answer 3

• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

This hierarchy helps in organizing biological diversity.

Question 4

What are the three domains used in modern classification?

Answer 4

• Bacteria
• Archaea
• Eukarya

Scientists primarily use this three-domain system.

Question 5

What characterizes plants in the domain Eukarya?

Answer 5

• Multicellular
• Autotrophs
• Use photosynthesis
• Cell walls made of cellulose

These traits define their role in ecosystems.

Question 6

What defines animals in the domain Eukarya?

Answer 6

• Multicellular
• Heterotrophs
• Lack cell walls
• Mostly motile

Animals play various roles in food webs.

Question 7

What are the characteristics of fungi?

Answer 7

• Mostly multicellular
• Heterotrophic decomposers
• Cell walls made of chitin

Fungi are essential for nutrient cycling in ecosystems.

Question 8

What are protists?

Answer 8

A diverse group of eukaryotes that do not fit into other kingdoms

They are not considered a cohesive ‘kingdom’ due to their vast diversity.

Question 9

What are cladograms and phylogenetic trees used for?

Answer 9

To show ancestral relationships and evolutionary history

They are tree-like diagrams that help visualize evolutionary connections.

Question 10

What distinguishes a phylogenetic tree from a cladogram?

Answer 10

Backed by molecular evidence (DNA) and branch lengths can represent time

This provides a more accurate representation of evolutionary relationships.

Question 11

Define a clade.

Answer 11

A group that includes a single common ancestor and all of its descendants

Clades are important for understanding evolutionary relationships.

Question 12

What do nodes represent in a phylogenetic tree?

Answer 12

A junction where two lines meet, symbolizing the last common ancestor

Nodes are critical for tracing evolutionary history.

Question 13

What are sister taxa?

Answer 13

Any two groups derived from the same common ancestral node

They share a more recent common ancestor than with other groups.

Question 14

What are derived characteristics?

Answer 14

Specific traits that appear in a lineage and are passed to descendants

These traits help scientists group organisms in a nested hierarchy.